Blood flow reducer for cardiovascular treatment

ABSTRACT

A blood flow reducing assembly includes a catheter shaft and an expandable occlusion member assembled with the catheter shaft. The expandable occlusion member includes foldable protrusions. One or more manipulation members are connected to the foldable protrusions and operative to move the foldable protrusions closer to or further away from one other. Movement of the foldable protrusions modifies occlusion ability of the foldable protrusions.

This application is a continuation of the PCT/IB2016/055763, filed Sep.27, 2016, which claims the benefit of priority to U.S. ProvisionalApplication No. 62/252,599, filed Nov. 9, 2015, the contents of each areherein incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention generally relates to apparatus and methods foraltering blood flow or for altering or affecting preload and afterloadin the cardiovascular system, such as to treat different conditions,such as but not limited to, venous hypertension or pulmonary edema inacute CHF (chronic heart failure) patients.

BACKGROUND OF THE INVENTION

Pulmonary edema, a medical emergency, is an accumulation of fluid in thelungs. Pulmonary edema is often caused by congestive heart failure. Whenthe heart is not able to pump efficiently, blood can back up into theveins that take blood through the lungs.

As the pressure in these blood vessels increases, fluid is pushed intothe air spaces (alveoli) in the lungs. This fluid reduces normal oxygenmovement through the lungs. These two factors combine to cause shortnessof breath.

Failure of the left side of the heart (left ventricle) causes blood toaccumulate in the veins of the lungs (pulmonary veins), producing adangerous rise in blood pressure within these veins. Sustained highpressure in the pulmonary veins eventually forces some fluid from theblood into the interstitial space and eventually to the surroundingmicroscopic air sacs (alveoli), which transfer oxygen to thebloodstream. As the alveoli fill with fluid, they can no longer provideadequate amounts of oxygen to the body.

Symptoms, especially severe breathing difficulty, develop over thecourse of a few hours and may be life-threatening. Although the outlookfor pulmonary edema is favorable if the underlying disorder is treatedin a timely fashion, the overall outcome for the patient depends uponthe nature of the underlying disorder. Adults at high risk for heartfailure are most commonly affected.

Typical treatment for patients presenting with pulmonary edema as aresult of CHF is the administration of diuretic drugs, designed toreduce preload, which is described as the mechanical state of the heartat the end of diastole, the magnitude of the maximal (end-diastolic)ventricular volume or the end-diastolic pressure stretching theventricles. In addition, vasodilation drugs are administered so as toreduce afterload—or the pressure against which the ventricle ejectsblood.

SUMMARY OF THE INVENTION

The present invention seeks to provide apparatus and methods foraltering or affecting blood flow or for altering or affecting preloadand afterload in the cardiovascular system, such as to treat differentconditions, such as but not limited to, pulmonary edema in acute CHF(chronic heart failure) patients or venous hypertension and otherconditions.

In one embodiment, the blood flow reducing assembly includes aself-expandable element located at a distal end of an indwellingcatheter. The self-expandable element has a distal end with a pluralityof circumferentially placed, inwardly folding elements with hingemembers, which allow the foldable elements to bend inwards (inwardsradially). The hinge members permit the foldable elements to fold withminimal effect on the open diameter of the cylindrical section of theself-expandable elements.

The foldable elements (and in certain embodiments, some of theself-expandable elements) are coated or covered with a membrane or othercovering, which is impervious to blood flow. The expandable distal endmay be covered or coated while the foldable arms are in a semi-closedposition so as to minimize excess material between the foldable arms asthe reducer is being closed.

The degree of closure of the device (or the degree of inward folding ofthe foldable elements) is controlled by an operator using a handlelocated at the proximal end of the catheter. The handle may have anindicator showing the degree of closure of the reducer device.

The reducer may cause a Bernoulli effect on the blood flow, with a jetflow exiting its central opening.

The reducer can be manipulated from an open to a fully or partiallyclosed position.

There is provided in accordance with a non-limiting embodiment of theinvention a blood flow reducing assembly including a catheter shaft, anexpandable occlusion member assembled with the catheter shaft, theexpandable occlusion member including loops, and manipulation membersconnected to the loops and operative to move the loops closer to orfurther away from one other, wherein movement of the loops modifiesocclusion ability of the loops.

In accordance with an embodiment of the invention movement of the loopscloser to one another increases occlusion ability of the loops andmovement of the loops further from one another decreases occlusionability of the loops.

In accordance with one non-limiting embodiment of the invention, theocclusion member includes interconnecting struts and the loops areconnected to at least some of the struts by hinge members, which allowthe loops to pivot with respect to the struts in one or more directions.The hinge members may be circumferentially distributed about distal endsof some or all of the struts. The loops may be extendable axially fromthe hinge members in a fully open position or are foldable inwardstowards each other in a partially or fully closed position.

In accordance with an embodiment of the invention a covering at leastpartially covers the expandable occlusion member, the covering beingimpervious to blood flow.

In accordance with an embodiment of the invention the manipulationmembers include one or more connecting links connected to the loops, theconnecting links extending to a handle located at a proximal end of thecatheter shaft, wherein manipulation of the handle moves the loops tomodify occlusion ability of the loops. When the loops are moved closerto one another, a space called an orifice is left open in the covering.

In accordance with an embodiment of the invention an indicator is on thehandle configured to indicate a degree of closure of the loops.

In accordance with another non-limiting embodiment of the invention thecatheter shaft includes a telescoping shaft that includes an inner shaftarranged to slide in an outer shaft, and the loops include helical loopspositioned between proximal and distal ends of the occlusion member, theproximal end of the occlusion member being secured to one of the innerand outer shafts and the distal end of the occlusion member beingsecured to the other one of the inner and outer shafts, and whereindecreasing a distance between the proximal and distal ends causes theloops of the occlusion member to bunch together, and wherein themanipulation members are the inner and outer shafts.

In accordance with an embodiment of the invention the expandableocclusion member includes a balloon with a portion formed into theloops.

The expandable occlusion member may be self-expanding or fluidlyexpandable, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified pictorial illustration of a blood flow reducingassembly, constructed and operative in accordance with a non-limitingembodiment of the invention;

FIGS. 2A and 2B are simplified pictorial illustrations of the blood flowreducing assembly in full flow and restricted flow (e.g., closed oralmost closed) positions, respectively;

FIG. 3 is a simplified pictorial illustration of the blood flow reducingassembly mounted on a shaft connected to a manipulating handle, inaccordance with a non-limiting embodiment of the invention;

FIG. 4 is a simplified pictorial illustration of the manipulatinghandle, showing an indicator of the degree of closure;

FIG. 5 is a simplified pictorial illustration of the blood flow reducingassembly mounted on the shaft and introduced into a body lumen, inaccordance with a non-limiting embodiment of the invention;

FIG. 6 is a simplified pictorial illustration of a blood flow reducingassembly, constructed and operative in accordance with anothernon-limiting embodiment of the invention;

FIG. 7A is a simplified pictorial illustration of loops of the bloodflow reducing assembly partially bunched together and partially expandedradially outwards to achieve partial occlusion;

FIG. 7B is a simplified pictorial illustration of the loops fullybunched together and fully expanded radially outwards to reach maximumocclusion;

FIG. 8 is a simplified pictorial illustration of the blood flow reducingassembly of FIGS. 6-7B mounted on the shaft and introduced into a bodylumen, in accordance with a non-limiting embodiment of the invention;and

FIG. 9 is a simplified pictorial illustration of a blood flow reducingassembly, constructed and operative in accordance with anothernon-limiting embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIG. 1, which illustrates a blood flow reducingassembly 10, constructed and operative in accordance with a non-limitingembodiment of the invention.

Assembly 10 includes a shaft, such as a flexible catheter shaft 12, andan expandable occlusion member 14 assembled with shaft 12. The occlusionmember 14 may be initially disposed in shaft 12 and deployed out ofshaft 12 such as by pushing occlusion member 14 out of shaft 12.Alternatively, occlusion member 14 may be mounted at the distal end ofshaft 12 (not inside shaft 12). The expandable occlusion member 14 maybe self-expanding (e.g., constructed of a shape memory material, such asbut not limited to, nitinol) or expandable by mechanical means (e.g.,wires that push/pull expandable elements) or expandable by fluid means(e.g., hydraulic or pneumatic inflation/deflation of flexible members,such as but not limited to, balloons).

The expandable occlusion member 14 may expand radially (and/or axially)and conform to the shape of the body lumen (e.g., blood vessel) in whichit is deployed. The expandable occlusion member 14 may be generallycylindrical in shape and having a diameter 14 a corresponding thereto(although other shapes are within the scope of the invention). Theexpanded size of occlusion member 14 may be greater than the internalperimeter of the body lumen, so that occlusion member 14 may be used toremodel the shape of the body lumen.

In this embodiment, the occlusion member 14 is constructed ofinterconnecting struts 16, such as wires or other slender elements,which may be bent or otherwise formed into loops that are interconnectedat wire folds 18. As shown in FIG. 1, the occlusion member/elementincludes a proximal portion 11 with an initial diameter 12 a, which maybe mounted the distal end portion 12 b of the shaft 12, and a pluralityof openings 11 a formed by the interconnecting struts 16. Such openings,as shown in FIG. 5, allow blood to flow into the occlusion element. Thisstructure of interconnecting struts 16 can be easily compressed andsubsequently expanded to a predetermined shape.

The expandable occlusion member 14 may include, as shown in FIG. 1,circumferentially arranged, distally projecting and radially inwardlyfoldable protrusions 20, arranged on a distal end of the occlusionmember, which may be formed as loops. Specifically, as shown in FIG. 1,each foldable protrusion may comprise, for example, a first strut 23 aconnected, at a proximal end, to the distal end of one of thecorresponding distally arranged, interconnecting struts 16, andconnected, at a distal end, to proximal ends of a pair of second struts23 b, where, as shown, the distal ends of the pair of second struts mayalso be connected. The foldable protrusions 20 may be connected to atleast some (or all) of the struts 16. In the illustrated embodiment,foldable protrusion 20 is connected to the distal end of the strut 16 bya hinge member 22, which allows the foldable protrusion 20 to pivotabout the distal end of the strut 16 in one or more directions. Hingemembers 22 are circumferentially distributed about the distal ends ofsome or all of the struts 16. The foldable protrusions 20 can extendaxially from hinge members 22 in a fully open position or can foldinwards towards each other in a partially or fully closed position.

A covering 24 is provided at the distal end of assembly 10. Covering 24may cover the foldable protrusions 20 and may also cover part of thedistal ends of the struts 16 and part of the hinge members 22 or otherparts of occlusion member 14. Covering 24 may be a membrane which isimpervious to blood flow. One or more connecting links 26, such as wiresor threads and the like, may be connected to (e.g., the distal end of)each of the foldable protrusions 20. The connecting links 26 extendthrough the axial length of the catheter shaft 12 to a handle 28 (FIG.3) located at a proximal end of shaft 12. Handle 28 includes a controlknob 30, which may be connected to an internal controllable spindleconnected to connecting links 26. The control knob 30 can be used topull or otherwise manipulate connecting links 26, thereby pulling thefoldable protrusions 20 inwards in a radial direction, effectivelycreating a resistance to the flow in the body lumen. In other words,movement of the foldable protrusions 20 closer to one another creates orincreases occlusion of the flow in the body lumen.

FIG. 2A illustrates foldable protrusions 20 extended axially from hingemembers 22 in a fully open position. The connecting links 26 have notbeen pulled inwards. FIG. 2B illustrates foldable protrusions 20 foldedinwards towards each other in a partially or fully closed position. Theconnecting links 26 have been pulled inwards to fold the foldableprotrusions 20 inwards towards each other. The connecting links 26 aremanipulation members that modify the occlusion ability of foldableprotrusions 20. The degree of closure can be controlled by handle 28(control knob 30). As seen in FIGS. 3 and 4, an indicator 32 may beprovided on handle 28 to indicate the degree of closure.

When the foldable protrusions 20 are brought to a closed (or inwardposition), flow downstream of the foldable protrusions 20 and occlusionmember 14 is reduced. The blood flow exits the flow reducer by flowingthrough space left open in covering 24 (referred to as orifice 34—FIG.2B, having an associated diameter), that is, through the center wherethe foldable protrusions 20 are not fully folded inwardly. The bloodthus flows from a relatively large diameter of the distal elements 14through the relatively small diameter of orifice 34 and then back to thebody lumen, which has a large diameter than orifice 34. This creates aVenturi effect (based on the Bernoulli effect), in which the flowthrough orifice 34 has a lower pressure and higher velocity, which canbe used to affect the pressure regime directly downstream of the bloodflow reducing assembly 10.

Reference is now made to FIG. 5, which illustrates the blood flowreducing assembly 10 mounted on shaft 12 and introduced into a bodylumen, in accordance with a non-limiting embodiment of the invention.The assembly is shown introduced into a blood vessel leading to thekidneys, upstream of the renal veins.

As described above, when assembly 10 is in its closed position, a jetflow of blood may flow through the orifice 34 generally towards thecenter of the inferior vena cava (IVC). Because of the Bernoulli effect,a region near the center of the IVC is created which has increased bloodvelocity and reduced pressure, which draws blood from the renal veins(increasing pressure drop over the kidneys). The assembly 10 can poolblood in the lower extremities and reduce the flow of blood into theright atrium which reduces preload.

The flow restriction can thus be used to control the volume, pressure orvenous capacitance of blood returning to the right atrium of the heartvia the inferior vena cava and/or the superior vena cava, thereby todecrease venous return. By controlled obstruction of the IVC, SVC orboth, it is surmised that blood may pool in the venous system, thusdecreasing venous blood return to the right atrium and affectingpreload.

Reference is now made to FIGS. 6-7B, which illustrate a blood flowreducing assembly 60, constructed and operative in accordance withanother non-limiting embodiment of the invention.

Assembly 60 includes a shaft, such as a flexible catheter shaft 62, andan expandable occlusion member 64 assembled with shaft 62. In theillustrated embodiment, catheter shaft 62 is a telescoping shaft thatincludes an inner shaft 65 arranged to slide in an outer shaft 66. Theocclusion member 64 may be initially disposed in shaft 62 (such as beingwrapped around a portion of inner shaft 65) and deployed out of shaft 62such as by pushing occlusion member 64 out of shaft 62. Outer shaft 66may be concentric with inner shaft 65.

In the illustrated embodiment, expandable occlusion member 64 is helicalhaving multiple coils or loops 68 positioned between proximal and distalends 61 and 63, respectively, of occlusion member 64. The proximal end61 is secured to outer shaft 66 and the distal end 63 is secured toinner shaft 65 (alternatively, the opposite may be done). By suitablelongitudinal axial movement of either inner shaft 65 or outer shaft 66,the distance between proximal end 61 and distal end 63 is eitherdecreased or increased. Decreasing the distance between proximal end 61and distal end 63 causes the loops 68 of occlusion member 64 to bunchtogether. FIG. 7A shows the loops 68 partially bunched together andpartially expanded radially outwards thus achieving partial occlusion,and FIG. 7B shows the loops 68 fully bunched together and fully expandedradially outwards, thus reaching maximum occlusion. FIG. 6 shows themaximum distance between proximal end 61 and distal end 63, in whichcase the loops 68 of occlusion member 64 are snugly wrapped around innershaft 65 and present minimum occlusion.

As in the previous embodiment, a control knob (not shown) can be used tomanipulate the inner and outer shafts to expand or contract the loops 68to increase or decrease resistance to the flow in a body lumen 69.Movement of the loops 68 closer to one another creates or increasesocclusion of the flow in the body lumen 69. The inner and outer shafts65 and 66 are manipulation members that modify the occlusion ability ofloops 68.

In the illustrated embodiment, the expandable and helical occlusionmember 64 is constructed of a balloon, a portion of which is wound intoloops 68. The balloon may be hydraulically or pneumatically inflated anddeflated, and as such, its stiffness can be controlled by the amount itis inflated. Alternatively, the expandable and helical occlusion member64 may be self-expanding (e.g., constructed of a shape memory material,such as but not limited to, nitinol).

The balloon may be introduced through body lumen 69 while in thedeflated state and positioned using methods known in the art. Fiduciarymarkers, such as but not limited to radiopaque markers or opticallysensed markers, may be placed on the device at selected areas to assistthe placement of the device. Once in place, the spiral balloon isinflated, creating a helical flow occlusion member which can disrupt orocclude blood flow in the anterograde direction without completelyoccluding the vessel.

Reference is now made to FIG. 8, which illustrates the blood flowreducing assembly 60 introduced into body lumen 69, in accordance with anon-limiting embodiment of the invention. The assembly is shownintroduced into a blood vessel leading to the kidneys, upstream of therenal veins.

Reference is now made to FIG. 9, which illustrates another blood flowreducing assembly of the invention in which an expandable occlusionmember 90 is placed into a body lumen such as inferior vena cava 74. Theexpandable occlusion member 90 may be a conical element as shown, but itcan also be a flat orifice. The expandable occlusion member 90 is placednear the inlet of the renal veins 73 thus creating an area of reducedpressure at the distal end of a conical member which has a distal endsmaller in diameter than its proximal end. The area of lower pressure inthe inlet area of the renal vein inlets increases the overall pressuregradient experienced by the kidneys 72.

In the embodiment of FIG. 9, the expandable occlusion member 90 is atruncated conical element, provided with proximal and distal ends 86 and87, wherein the proximal end 86 is located upstream of the conicalelement relative to antegrade flow and the distal end 87 is locateddownstream of the conical element, and the proximal end of the conicalelement has a larger diameter than the distal end of the truncatedconical element. The truncated conical element is located on an innershaft of a delivery catheter 92 having one or more internal shafts, andone or more external shafts, whereby the external shaft can govern theradial expansion of the truncated conical section by the relativemovement of the external shaft relative to the inner shafts of thedelivery catheter (as described above for the embodiment of FIGS. 6-8).The proximal end of the truncated conical element may or may not comeinto contact with the tissue of the surrounding body lumen. The anglesdefined by the conical wall section to the central axis of the truncatedconical element can vary, without limitation, from 90°—which wouldcharacterize a flat element with a critical orifice, to 5° which wouldmake for an elongated conical element. The expandable occlusion memberdescribed may also take more complex forms other than straight truncatedcones.

The blood entering the proximal end of the truncated conical element(expandable occlusion member) will gradually accelerate as it flows inthe antegrade direction through the truncated conical element. Thevelocity of the fluid jet exiting the distal end of the conical elementas it discharges back into the body lumen will be greater than thevelocity of the fluid at the proximal end of the conical element andwill therefore have a lower pressure than that at the proximal end ofthe device. The flow through the truncated conical element or throughthe orifice described above can be described by using Bernoulli'sequation:

${p_{1} - p_{2}} = {\frac{\rho}{2}\left( {v_{2}^{2} - v_{1}^{2}} \right)}$

Where:

P₁ and P₂ are the pressures before and at the constriction respectively

ρ is the density of blood

V₁ and V₂ are the blood velocities before and at the constrictionrespectively

Placement of this device in the inferior vena cava, caudal to the inletof the renal veins, creates a lower pressure zone in the area, therebyincreasing the pressure gradient on the kidneys and improving renalfunction.

What is claimed is:
 1. An adjustable blood flow reducing system foradjustably reducing blood flow within a blood vessel, the systemcomprising: a handle; a catheter shaft configured to fit within a bloodvessel, the blood vessel including a blood vessel diameter (BVD); aplurality of connecting links configured to extend from the handle andthrough the catheter shaft; and an expandable element configured to beplaced within the blood vessel, the expandable element arranged on adistal end portion of the catheter shaft and operatively connected tothe handle via at least the connecting links, the expandable elementcomprising: a plurality of interconnecting struts forming, at least whenexpanded: a first proximal section mounted on the distal end portion ofthe catheter shaft, wherein the first proximal section has an initialdiameter corresponding approximately to the distal end portion of thecatheter shaft, a cylindrical section following the proximal section andhaving a first diameter, the first diameter corresponding at leastapproximately to the BVD, wherein the initial diameter of the proximalsection distally increases up to the first diameter, a plurality ofcircumferentially arranged, distally projecting and radial inwardlyfoldable protrusions arranged on a distal end of the cylindrical sectionand adjustable relative thereto via movement of the connecting links,each foldable protrusion comprising a first single strut connected at afirst end to a portion of the distal end of the cylindrical section andconnected at a second end to first ends of a pair of associated strutshaving distally connected second ends thereby forming an enclosed areatherebetween, and a blood flow orifice having a second diameter formedby distal ends of the foldable protrusions, and a blood impervious coverconfigured to cover at least a distal portion of the cylindrical sectionand the foldable protrusions, wherein the expandable element isconfigured such that upon implantation within the blood vessel: theorifice is arranged downstream relative to blood flow of the bloodvessel, blood flows into the expandable element via openings formedbetween the interconnected struts of the proximal section, theconnecting links are configured to pivot the foldable protrusions viamanipulation of the handle so as to change the second diameter of theorifice for producing a desired reduced blood flow from the orificewhile maintaining the first diameter of the cylindrical section withinthe vessel, and the second diameter decreases as the foldableprotrusions fold inwardly.
 2. The system according to claim 1, whereinthe foldable protrusions are each configured in the form of a loop. 3.The system of claim 1, wherein the expandable element includes aself-expandable portion.
 4. The system of claim 3, wherein theself-expandable portion is made from nitinol.
 5. The system of claim 1,wherein the handle includes a control knob.
 6. The system of claim 1,wherein the handle includes a spindle operably connected to theplurality of connecting links.
 7. The system of claim 1, wherein thehandle includes a control knob and a spindle.
 8. The system of claim 7,wherein the control knob is operably connected to the spindle.
 9. Thesystem of claim 8, wherein the spindle is operably connected to theplurality of connecting links.
 10. The system of claim 5, wherein thecontrol knob is configured to pull or otherwise manipulate connectinglinks via the spindle so as to move the protrusions to effect the changeof the second diameter.